Yesterday, Prince William and Prince Harry paid tribute to their beloved mother by placing flowers at the front gates of Kensington Palace, Diana's former home.

In the lead up to the anniversary, the princes have been speaking candidly about the grief they felt over losing their mum.

“[I] refused to accept it. There was no sudden outpour of grief. I don’t think anybody in that position at that age would be able to understand the concept of what that actually means, going forward,” Prince William recalled in BC1's new documentary, Diana, 7 Days.

“I remember feeling completely numb, disoriented, dizzy - and you feel very very confused,” he continued. “And you keep asking yourself, ‘Why me?’ the whole time. ‘Why? What have I done, why has this happened to us?’”